The invention relates generally to tape drives and more specifically to tape drives employing fine-coarse positioners. More specifically, the invention relates to tape drives using fine-coarse positioners and having more than one head gap to provide enhanced bandwidth.
Magnetic tape data storage devices, or tape drives, have long been used for storing large quantities of computer data. More recently, as disc drives have become increasingly faster, tape drives have become more popular for long term data storage and backup.
The storage and recovery of data from a tape drive is accomplished via a gap in the read/write head. The data is stored in the form of magnetic flux reversals within the magnetic coating on the tape. To maximize flux reversal sharpness, and therefore maximize the amplitude of the data pulses read, the length of the head gap is aligned as accurately as possible with the tape as it moves laterally past the head.
Frequently, tape drives include a multi gap head, with one head gap used to write data and another head gap used to read the just-written data to ensure accuracy. The purpose of the second head gap is to read or verify the written data recorded by the first head gap while the tape is in motion in a forward direction. Similarly, while the tape moves in a reverse direction, the second head gap writes the data and the first head gap verifies the data. The terms forward and reverse direction, as well as the notations first and second head gap are relative terms defined in relation to each other.
If it is desired that the tape drive could read/write with the tape moving in either direction, an additional head gap is required. In order to provide an optimal interface between the head and the tape, the head gap is raised in relation to the rest of the head. This raised area is better known as a rail. A head with only one gap would have a single rail while, for example, a head with two gaps would have two rails. The distance between the rails is as short as possible and is currently limited by manufacturing and fabrication technology.
As long as there is only one gap per rail, the transfer rate of a tape drive is a function of the linear speed of the tape moving past the head and the recording density, or bits per inch, of the data present on the tape. The transfer rate represents the amount of data that can be recorded or read in a given period of time. Unfortunately, both linear tape speed and recording density are limited by available technology. One solution is to increase the transfer rate by providing multiple writing heads. Consequently, a tape drive with a very high transfer rate would have multiple gaps per rail.
While this would certainly increase the transfer rate, certain mechanical difficulties arise in the design of a flexible printed circuit for a head that would support an increased transfer rate. The purpose of the flexible printed circuit is to operably connect the head gap to a main printed circuit board of the tape drive. For each magnetic gap, there are five circuits or lines required between the head gap and the main printed circuit board, i.e., 2 for the read gap (read+ and read xe2x88x92); 2 for the write gap (write+ and writexe2x88x92); and 1 shield or ground.
Thus, the circuitry requirements for even a single gap head are significant. If the single gap head was required to read and write simultaneously, the circuitry requirements double. It is anticipated, however, that future tape drives will have substantially more gaps per rail as expected transfer rates reach the 15 to 20 megabyte per second range.
For example, a tape drive with 10 head gaps per rail is anticipated. Such a head would require 50 circuits or lines. If the drive has read and write capabilities, the head would utilize 100 circuits. As the flexible printed circuit board becomes larger, it becomes less flexible, which can be a significant detriment as the head is required to move laterally across the width of the tape to access and follow a desired data track. A typical tape has about 400 data tracks across the width of the tape.
A need remains for a tape drive with a high transfer rate. A need remains for a tape drive that minimizes the stiffness caused by substantial flexible printed circuits.
A first aspect of the invention is found in a method of increasing the transfer rate of a magnetic tape drive that has a fine positioner, a coarse positioner, and main control circuitry. The method includes providing a head having at least one rail, wherein the rail has at least one head gap, mounting the head in an assembly including a fine positioner and a coarse positioner, and operatively connecting the head to the main control circuitry of the tape drive via a flexible printed circuit that is configured to provide a predetermined level of stiffness.
A second aspect of the invention is found in a magnetic tape drive having an increased transfer rate. The drive includes a magnetic head having a minimum of two rails, each rail having a plurality of head gaps; wherein the head is arranged within and positioned by a head positioning apparatus including a fine positioner and a coarse positioner. The drive also includes flexible printed circuits that provide communication between the magnetic head and main control circuitry; wherein the flexible printed circuits have at least one loop that corresponds to the translation range of the head positioning apparatus.
A third aspect of the invention is found in a flex circuit for coupling a head of a tape drive to a main circuit board that provides translation commands to the head of the tape drive. The flex circuit includes a fine positioner loop having a shape that is designed to reduce stiffness in the flex circuit and a coarse positioner loop coupled to the fine positioner loop, the coarse positioner having a shape that is designed to reduce stiffness in the flex circuit.
These and other features as well as advantages that characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.